This application requests funding for continued support of the Multiethnic Cohort Study which was established in Hawaii and Los Angeles in 1993-96 to explore the relationship of diet and other lifestyle factors to cancer. The cohort is comprised of more than 215,000 men and women primarily of African American, Japanese, Latino, Native Hawaiian and Caucasian origin, and is unique among existing cohort studies in its ethnic diversity and representation of minority populations. At entry, each participant completed a 26-page mail questionnaire that included an extensive quantitative diet history, as well as other demographic, medical, and lifestyle information. Multiple 24-hour diet recalls were collected on more than 2,000 of the participants in a calibration study designed to permit correction of nutrient intake estimates for measurement error. In the current cycle (1998-2003), a brief follow-up questionnaire to update selected dietary and non-dietary baseline information was completed by more than 80 percent of the participants; in the next cycle, the baseline dietary questionnaire will be repeated. Out-migration rates after 7 years were low (< 5 percent), supporting the use of computer linkage with the population-based cancer registries in Hawaii and California to identify incident cases; more than 25,000 cases of breast, prostate, colorectum and lung cancer are expected by the year 2007. Based on an average 4 years of follow-up, some preliminary dietary findings included: positive association of alcohol with breast cancer, dairy products with prostate cancer, and saturated fat with lung cancer; and inverse association of legumes with breast cancer, carotenoids and certain vegetables with lung cancer, and dietary fiber and folate with colorectal cancer. In the next cycle, the larger numbers of incident cases will enable us to further examine these dietary relationships by ethnicity and stage of disease, to examine other cancer sites (pancreas, bladder, ovary, endometrium), and to contribute to analyses of gene-diet interactions. In addition, new information from the follow-up questionnaire and enhancements to the food composition database will be used to directly test the relationship of flavonoids and heterocyclic amines to colorectal, lung, bladder and other cancers. We will also test hypotheses related to use of exogenous hormones and cancers of the breast, ovary and colorectum; and use of NSAIDs and cancers oft he colorectum, lung, breast and ovary. A methodological aim, utilizing biochemical measurements on 750 members of the cohort, will develop new dietary exposure variables to improve testing of etiologic hypotheses. Findings from the Multiethnic Cohort Study should help not only to identify dietary and other risk factors for cancer, but also to better understand the basis for ethnic variations in cancer incidence.